A new “party drug” has arrived on the scene to strike dread into the hearts of parents with teenage children. It’s called mephedrone and it goes also by countless weird nicknames including “miaow”, “bubble”, “drone” and “M-Cat”. It is chemically related both to amphetamine and to the cathinones, the active ingredients of the shrub khat, whose leaves are chewed as a stimulant in Somalia, Yemen and Ethiopia. (It has nothing to do with the opioid medicine methadone.)

For the time being, mephedrone is legal, as long as it is packaged – disingenuously, but to comply with medicines legislation – as “plant food: not for human consumption”. Mind you, even the internet dealers do not expect this relaxed state of affairs to continue for much longer. On Monday, Louis Wainwright, 18, and Nicholas Smith, 19, two friends from Humberside, died after a night on the town. Police arelinking their deaths to mephedrone. As it happens, one of the people they arrested in connection with the deaths was reported also to have been treated in hospital for side-effects of mephedrone.

Mr Smith’s father, Tony, said: “I don’t want him to be labelled a druggie because he wasn’t. He was just on a night out with friends enjoying himself – a normal, caring, hard-working lad. I just don’t want any other family to go through this or any other kids to die because of this. He was 19, for God’s sake.”

Like cocaine and speed, mephedrone comes as a white or yellowish powder. Sniff it or swallow it in a capsule and you can expect to see similar effects to those other stimulants. You will feel more lively and chatty to begin with, with raised heart rate and elevated mood. Then, with increased doses, you would expect to see the less desirable effects, such as teeth-grinding, anxiety, saucer-sized pupils. There are reports of burning throat, nosebleeds and numb extremities. In the worst cases you get agitation, paranoia, seizures and, ultimately, death.

Yesterday, head teachers were calling for the drug to be banned at once, even if that meant criminalising pupils. Lord Mandelson, who had not heard of mephedrone before, promised that its legality would be “speedily” examined and the Government would “take any action that is needed”.

Israel, Sweden and Denmark have already outlawed the compound. In Guernsey the authorities have prohibited its importation and are now considering classifying it as a Class A substance, with the highest possible penalties for possession or distribution.

It is a complex area, though. The Government, responding to public anxieties, will no doubt ban this particular substance. But is that actually going to protect schoolchildren from experimenting with drugs? Someone, somewhere, concocted mephedrone in a laboratory by tweaking existing chemicals with the sole purpose of staying one step ahead of the drug laws. How long will it be before they produce another variant? Even if mephedrone is outlawed, exotic websites such as the self-styled “UK’s no 1 headshop” will continue to offer a drop-down menu of items including “legal hallucinogens”, “legal Ecstasy” and “legal speed”, with next-day delivery.

What can we do to discourage young people from endangering their lives with reckless behaviour? Professor David Nutt, who was sacked by the Government last October for contradicting its drugs message, thinks all legal highs should be handled with caution precisely because they are such an unknown quantity. In December, he told a newspaper: “I know it’s controversial to say it, but people are better off taking Ecstasy or amphetamines than those we know nothing about. Who knows what’s in [mephedrone] when you buy it? We don’t have a testing system. It could be very dangerous, we just don’t know. These chemicals have never been put into animals, let alone humans.”

Of course, it was Professor Nutt’s tendency to speak his mind that lost him his job as the head of the Advisory Council on the Misuse of Drugs (ACMD). He very publicly disagreed with the Government on the reclassification of cannabis as a Class B drug. He thought Ecstasy should be downgraded. And in a paper in a learned journal, he startled people by saying there was “not much difference” between the harm caused by riding horses – about 10 deaths a year – and the harm caused by Ecstasy.

He has only ever argued that policy should be based on solid scientific evidence. Drugs, though, is an area where most politicians are not thinking of the evidence only. They are also trying to look robust and impressive in tomorrow’s headlines.

Martin Barnes, the chief executive of the charity Drugscope, told me that in his view it was “likely” that the ACMD would recommend a ban when it announces the results of ongoing investigations into mephedrone on March 29. That would help, he thinks, with the current anomaly where a dangerous drug is being distributed to young people with virtually no controls. But there are “no silver bullets”.

“The evidence is quite compelling for [mephedrone’s] harmfulness,” he said. Banning it under the Misuse of Drugs Act would address the immediate issue of its free availability. But ultimately, Mr Barnes thinks that “education and information” are vital.

He is surely right. There is something irrational and childish about the way we discuss drugs in public. For one thing, simply trying to scare young people does not work. If an adult tells teenagers that drugs will kill them, they switch off their minds and close their ears. They only need to look at their friends, who have taken drugs and survived, to know that drugs do not all kill instantly. And, in any case, no teenager thinks he is going to die.

Much better, surely, if we can bring ourselves to treat our children with respect and tell them the truth. How much more persuasive it would be to explain that, actually, yes, they would be pretty unlucky to die as a result of taking drugs. But they should bear in mind that, with mephedrone, they could have a horrendous time. They may feel sick and agitated, and unable to sleep. They may suffer awful hallucinations that won’t go away, and heart palpitations.

And we should tell them that no one has the slightest idea, for sure, what damage the stuff might inflict on the brain, the body and the nervous system in the long term. That taking it really is a bit like playing Russian roulette. Perhaps we could even inform teenagers that there are plenty of tried and tested, safer substances out there, from a good old gin and tonic upwards. But I wonder if we would tolerate a maverick head teacher, say, who spoke to his charges with such candour.

At 40, I am at a stage in life when a walk on the common with my wife and small children provides all the excitement I can handle. Youth, on the other hand, fears boredom above all, and craves stimulation, risk, sensation. At least, it was like that for me.

I well remember how I used to relish the instant hit of mood-altering substances, beginning with alcohol. When you’re young, sometimes you do not feel truly alive unless you are taking risks. The question for both schools and parents is how to enable children to gain a realistic appreciation of the different risks – of alcohol, drugs, cigarettes – and, ideally, to encourage them to take responsibility for themselves.

We must try to be realistic and honest. Adolescents will experiment with addictive substances. Most of them will emerge from the experience unscathed, more or less. But for some, the vulnerable ones, experimentation will turn into something darker – into “harmful use” as the textbooks call it, and then into dependency. Behaviour becomes compulsive and destructive, whether the substance is an illegal drug or alcohol or food.

This is addiction – when a desperate person starts worshipping a substance, or turning it into the primary relationship in their life and the primary source of pleasure. Then what happens is that the substance or the behaviour starts possessing the person. It’s preferable, is it not, that humans should gain this kind of satisfaction from other people, from meaningful work, perhaps from a spiritual life, and from families?

Politicians would do well to consider, first, how to talk to young people realistically about the dangers, and second, why some young people are more inclined than before to drink heavily or to take risks with drugs.

What is wrong? What is the underlying malaise? Outlawing mephedrone may well be a necessary expedient to protect children from harm in the short term. But banning a particular substance is only to deal with a symptom. You can be sure another compound will be along tomorrow.